// Copyright 2006 Google Inc.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//   http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
// Known Issues:
//
// * Patterns only support repeat.
// * Radial gradient are not implemented. The VML version of these look very
//   different from the canvas one.
// * Clipping paths are not implemented.
// * Coordsize. The width and height attribute have higher priority than the
//   width and height style values which isn't correct.
// * Painting mode isn't implemented.
// * Canvas width/height should is using content-box by default. IE in
//   Quirks mode will draw the canvas using border-box. Either change your
//   doctype to HTML5
//   (http://www.whatwg.org/specs/web-apps/current-work/#the-doctype)
//   or use Box Sizing Behavior from WebFX
//   (http://webfx.eae.net/dhtml/boxsizing/boxsizing.html)
// * Non uniform scaling does not correctly scale strokes.
// * Optimize. There is always room for speed improvements.
// AMD by kener.linfeng@gmail.com
// Optimized by https://github.com/pissang
// 
// NOTES http://jsperf.com/dom-attr-read-perf/2
// http://jsperf.com/arr-vs-obj-in-ie


// Only add this code if we do not already have a canvas implementation
if (!document.createElement('canvas').getContext) {
    (function () {
        // alias some functions to make (compiled) code shorter
        var m = Math;
        var mr = m.round;
        var ms = m.sin;
        var mc = m.cos;
        var abs = m.abs;
        var sqrt = m.sqrt;
        // this is used for sub pixel precision
        var Z = 10;
        var Z2 = Z / 2;
        var IE_VERSION = +navigator.userAgent.match(/MSIE ([\d.]+)?/)[1];
        var EPSILON = 0.00001;
        var isAroundZero = function (val) {
            return val > -EPSILON && val < EPSILON;
        };
        function isNotAroundZero(val) {
            return val > EPSILON || val < -EPSILON;
        }
        /**
   * This funtion is assigned to the <canvas> elements as element.getContext().
   * @this {HTMLElement}
   * @return {CanvasRenderingContext2D_}
   */
        function getContext() {
            return this.context_ || (this.context_ = new CanvasRenderingContext2D_(this));
        }
        var slice = Array.prototype.slice;
        /**
   * Binds a function to an object. The returned function will always use the
   * passed in {@code obj} as {@code this}.
   *
   * Example:
   *
   *   g = bind(f, obj, a, b)
   *   g(c, d) // will do f.call(obj, a, b, c, d)
   *
   * @param {Function} f The function to bind the object to
   * @param {Object} obj The object that should act as this when the function
   *     is called
   * @param {*} var_args Rest arguments that will be used as the initial
   *     arguments when the function is called
   * @return {Function} A new function that has bound this
   */
        function bind(f, obj, var_args) {
            var a = slice.call(arguments, 2);
            return function () {
                return f.apply(obj, a.concat(slice.call(arguments)));
            };
        }
        function encodeHtmlAttribute(s) {
            return String(s).replace(/&/g, '&amp;').replace(/"/g, '&quot;');
        }
        function addNamespace(doc, prefix, urn) {
            if (!doc.namespaces[prefix]) {
                // NOTES, It will not work proply if add '#default#VML' 
                // When using appendChild to add dom
                // doc.namespaces.add(prefix, urn, '#default#VML');
                doc.namespaces.add(prefix, urn);
            }
        }
        function addNamespacesAndStylesheet(doc) {
            addNamespace(doc, 'g_vml_', 'urn:schemas-microsoft-com:vml');
            addNamespace(doc, 'g_o_', 'urn:schemas-microsoft-com:office:office');
            // Setup default CSS.  Only add one style sheet per document
            if (!doc.styleSheets['ex_canvas_']) {
                var ss = doc.createStyleSheet();
                ss.owningElement.id = 'ex_canvas_';
                ss.cssText = 'canvas{display:inline-block;overflow:hidden;' + // default size is 300x150 in Gecko and Opera
                'text-align:left;width:300px;height:150px} .g_vml_ {behavior:url(#default#VML);}';
            }
        }
        function createVMLElement(tagName) {
            // NOTES Why using createElement needs to add behavior:url(#default#VML) in style
            var dom = document.createElement('<g_vml_:' + tagName + ' class="g_vml_">');
            return dom;
        }
        // Add namespaces and stylesheet at startup.
        addNamespacesAndStylesheet(document);
        var G_vmlCanvasManager_ = {
            init: function (opt_doc) {
                var doc = opt_doc || document;
                // Create a dummy element so that IE will allow canvas elements to be
                // recognized.
                doc.createElement('canvas');
                doc.attachEvent('onreadystatechange', bind(this.init_, this, doc));
            },
            init_: function (doc) {
                // find all canvas elements
                var els = doc.getElementsByTagName('canvas');
                for (var i = 0; i < els.length; i++) {
                    this.initElement(els[i]);
                }
            },
            /**
     * Public initializes a canvas element so that it can be used as canvas
     * element from now on. This is called automatically before the page is
     * loaded but if you are creating elements using createElement you need to
     * make sure this is called on the element.
     * @param {HTMLElement} el The canvas element to initialize.
     * @return {HTMLElement} the element that was created.
     */
            initElement: function (el) {
                if (!el.getContext) {
                    el.getContext = getContext;
                    // Add namespaces and stylesheet to document of the element.
                    addNamespacesAndStylesheet(el.ownerDocument);
                    // Remove fallback content. There is no way to hide text nodes so we
                    // just remove all childNodes. We could hide all elements and remove
                    // text nodes but who really cares about the fallback content.
                    el.innerHTML = '';
                    // do not use inline function because that will leak memory
                    el.attachEvent('onpropertychange', onPropertyChange);
                    el.attachEvent('onresize', onResize);
                    var attrs = el.attributes;
                    if (attrs.width && attrs.width.specified) {
                        // TODO: use runtimeStyle and coordsize
                        // el.getContext().setWidth_(attrs.width.nodeValue);
                        el.style.width = attrs.width.nodeValue + 'px';
                    } else {
                        el.width = el.clientWidth;
                    }
                    if (attrs.height && attrs.height.specified) {
                        // TODO: use runtimeStyle and coordsize
                        // el.getContext().setHeight_(attrs.height.nodeValue);
                        el.style.height = attrs.height.nodeValue + 'px';
                    } else {
                        el.height = el.clientHeight;
                    }    //el.getContext().setCoordsize_()
                }
                return el;
            }
        };
        function onPropertyChange(e) {
            var el = e.srcElement;
            switch (e.propertyName) {
            case 'width':
                el.getContext().clearRect();
                el.style.width = el.attributes.width.nodeValue + 'px';
                // In IE8 this does not trigger onresize.
                el.firstChild.style.width = el.clientWidth + 'px';
                break;
            case 'height':
                el.getContext().clearRect();
                el.style.height = el.attributes.height.nodeValue + 'px';
                el.firstChild.style.height = el.clientHeight + 'px';
                break;
            }
        }
        function onResize(e) {
            var el = e.srcElement;
            if (el.firstChild) {
                el.firstChild.style.width = el.clientWidth + 'px';
                el.firstChild.style.height = el.clientHeight + 'px';
            }
        }
        G_vmlCanvasManager_.init();
        // precompute "00" to "FF"
        var decToHex = [];
        for (var i = 0; i < 16; i++) {
            for (var j = 0; j < 16; j++) {
                decToHex[i * 16 + j] = i.toString(16) + j.toString(16);
            }
        }
        function createMatrixIdentity() {
            return [
                [
                    1,
                    0,
                    0
                ],
                [
                    0,
                    1,
                    0
                ],
                [
                    0,
                    0,
                    1
                ]
            ];
        }
        function matrixMultiply(m1, m2) {
            var result = createMatrixIdentity();
            for (var x = 0; x < 3; x++) {
                for (var y = 0; y < 3; y++) {
                    var sum = 0;
                    for (var z = 0; z < 3; z++) {
                        sum += m1[x][z] * m2[z][y];
                    }
                    result[x][y] = sum;
                }
            }
            return result;
        }
        function copyState(o1, o2) {
            o2.fillStyle = o1.fillStyle;
            o2.lineCap = o1.lineCap;
            o2.lineJoin = o1.lineJoin;
            o2.lineWidth = o1.lineWidth;
            o2.miterLimit = o1.miterLimit;
            o2.strokeStyle = o1.strokeStyle;
            o2.globalAlpha = o1.globalAlpha;
            o2.font = o1.font;
            o2.textAlign = o1.textAlign;
            o2.textBaseline = o1.textBaseline;
            o2.scaleX_ = o1.scaleX_;
            o2.scaleY_ = o1.scaleY_;
            o2.x_ = o1.x_;
            o2.y_ = o1.y_;
            o2.lineScale_ = o1.lineScale_;
        }
        var colorData = {
            aliceblue: '#F0F8FF',
            antiquewhite: '#FAEBD7',
            aquamarine: '#7FFFD4',
            azure: '#F0FFFF',
            beige: '#F5F5DC',
            bisque: '#FFE4C4',
            black: '#000000',
            blanchedalmond: '#FFEBCD',
            blueviolet: '#8A2BE2',
            brown: '#A52A2A',
            burlywood: '#DEB887',
            cadetblue: '#5F9EA0',
            chartreuse: '#7FFF00',
            chocolate: '#D2691E',
            coral: '#FF7F50',
            cornflowerblue: '#6495ED',
            cornsilk: '#FFF8DC',
            crimson: '#DC143C',
            cyan: '#00FFFF',
            darkblue: '#00008B',
            darkcyan: '#008B8B',
            darkgoldenrod: '#B8860B',
            darkgray: '#A9A9A9',
            darkgreen: '#006400',
            darkgrey: '#A9A9A9',
            darkkhaki: '#BDB76B',
            darkmagenta: '#8B008B',
            darkolivegreen: '#556B2F',
            darkorange: '#FF8C00',
            darkorchid: '#9932CC',
            darkred: '#8B0000',
            darksalmon: '#E9967A',
            darkseagreen: '#8FBC8F',
            darkslateblue: '#483D8B',
            darkslategray: '#2F4F4F',
            darkslategrey: '#2F4F4F',
            darkturquoise: '#00CED1',
            darkviolet: '#9400D3',
            deeppink: '#FF1493',
            deepskyblue: '#00BFFF',
            dimgray: '#696969',
            dimgrey: '#696969',
            dodgerblue: '#1E90FF',
            firebrick: '#B22222',
            floralwhite: '#FFFAF0',
            forestgreen: '#228B22',
            gainsboro: '#DCDCDC',
            ghostwhite: '#F8F8FF',
            gold: '#FFD700',
            goldenrod: '#DAA520',
            grey: '#808080',
            greenyellow: '#ADFF2F',
            honeydew: '#F0FFF0',
            hotpink: '#FF69B4',
            indianred: '#CD5C5C',
            indigo: '#4B0082',
            ivory: '#FFFFF0',
            khaki: '#F0E68C',
            lavender: '#E6E6FA',
            lavenderblush: '#FFF0F5',
            lawngreen: '#7CFC00',
            lemonchiffon: '#FFFACD',
            lightblue: '#ADD8E6',
            lightcoral: '#F08080',
            lightcyan: '#E0FFFF',
            lightgoldenrodyellow: '#FAFAD2',
            lightgreen: '#90EE90',
            lightgrey: '#D3D3D3',
            lightpink: '#FFB6C1',
            lightsalmon: '#FFA07A',
            lightseagreen: '#20B2AA',
            lightskyblue: '#87CEFA',
            lightslategray: '#778899',
            lightslategrey: '#778899',
            lightsteelblue: '#B0C4DE',
            lightyellow: '#FFFFE0',
            limegreen: '#32CD32',
            linen: '#FAF0E6',
            magenta: '#FF00FF',
            mediumaquamarine: '#66CDAA',
            mediumblue: '#0000CD',
            mediumorchid: '#BA55D3',
            mediumpurple: '#9370DB',
            mediumseagreen: '#3CB371',
            mediumslateblue: '#7B68EE',
            mediumspringgreen: '#00FA9A',
            mediumturquoise: '#48D1CC',
            mediumvioletred: '#C71585',
            midnightblue: '#191970',
            mintcream: '#F5FFFA',
            mistyrose: '#FFE4E1',
            moccasin: '#FFE4B5',
            navajowhite: '#FFDEAD',
            oldlace: '#FDF5E6',
            olivedrab: '#6B8E23',
            orange: '#FFA500',
            orangered: '#FF4500',
            orchid: '#DA70D6',
            palegoldenrod: '#EEE8AA',
            palegreen: '#98FB98',
            paleturquoise: '#AFEEEE',
            palevioletred: '#DB7093',
            papayawhip: '#FFEFD5',
            peachpuff: '#FFDAB9',
            peru: '#CD853F',
            pink: '#FFC0CB',
            plum: '#DDA0DD',
            powderblue: '#B0E0E6',
            rosybrown: '#BC8F8F',
            royalblue: '#4169E1',
            saddlebrown: '#8B4513',
            salmon: '#FA8072',
            sandybrown: '#F4A460',
            seagreen: '#2E8B57',
            seashell: '#FFF5EE',
            sienna: '#A0522D',
            skyblue: '#87CEEB',
            slateblue: '#6A5ACD',
            slategray: '#708090',
            slategrey: '#708090',
            snow: '#FFFAFA',
            springgreen: '#00FF7F',
            steelblue: '#4682B4',
            tan: '#D2B48C',
            thistle: '#D8BFD8',
            tomato: '#FF6347',
            turquoise: '#40E0D0',
            violet: '#EE82EE',
            wheat: '#F5DEB3',
            whitesmoke: '#F5F5F5',
            yellowgreen: '#9ACD32'
        };
        function getRgbHslContent(styleString) {
            var start = styleString.indexOf('(', 3);
            var end = styleString.indexOf(')', start + 1);
            var parts = styleString.substring(start + 1, end).split(',');
            // add alpha if needed
            if (parts.length != 4 || styleString.charAt(3) != 'a') {
                parts[3] = 1;
            }
            return parts;
        }
        function percent(s) {
            return parseFloat(s) / 100;
        }
        function clamp(v, min, max) {
            return Math.min(max, Math.max(min, v));
        }
        function hslToRgb(parts) {
            var r, g, b, h, s, l;
            h = parseFloat(parts[0]) / 360 % 360;
            if (h < 0)
                h++;
            s = clamp(percent(parts[1]), 0, 1);
            l = clamp(percent(parts[2]), 0, 1);
            if (s == 0) {
                r = g = b = l;    // achromatic
            } else {
                var q = l < 0.5 ? l * (1 + s) : l + s - l * s;
                var p = 2 * l - q;
                r = hueToRgb(p, q, h + 1 / 3);
                g = hueToRgb(p, q, h);
                b = hueToRgb(p, q, h - 1 / 3);
            }
            return '#' + decToHex[Math.floor(r * 255)] + decToHex[Math.floor(g * 255)] + decToHex[Math.floor(b * 255)];
        }
        function hueToRgb(m1, m2, h) {
            if (h < 0)
                h++;
            if (h > 1)
                h--;
            if (6 * h < 1)
                return m1 + (m2 - m1) * 6 * h;
            else if (2 * h < 1)
                return m2;
            else if (3 * h < 2)
                return m1 + (m2 - m1) * (2 / 3 - h) * 6;
            else
                return m1;
        }
        var processStyleCache = {};
        function processStyle(styleString) {
            if (styleString in processStyleCache) {
                return processStyleCache[styleString];
            }
            var str, alpha = 1;
            styleString = String(styleString);
            if (styleString.charAt(0) == '#') {
                str = styleString;
            } else if (/^rgb/.test(styleString)) {
                var parts = getRgbHslContent(styleString);
                var str = '#', n;
                for (var i = 0; i < 3; i++) {
                    if (parts[i].indexOf('%') != -1) {
                        n = Math.floor(percent(parts[i]) * 255);
                    } else {
                        n = +parts[i];
                    }
                    str += decToHex[clamp(n, 0, 255)];
                }
                alpha = +parts[3];
            } else if (/^hsl/.test(styleString)) {
                var parts = getRgbHslContent(styleString);
                str = hslToRgb(parts);
                alpha = parts[3];
            } else {
                str = colorData[styleString] || styleString;
            }
            return processStyleCache[styleString] = {
                color: str,
                alpha: alpha
            };
        }
        var DEFAULT_STYLE = {
            style: 'normal',
            variant: 'normal',
            weight: 'normal',
            size: 12,
            //10
            family: '微软雅黑'    //'sans-serif'
        };
        // Internal text style cache
        var fontStyleCache = {};
        function processFontStyle(styleString) {
            if (fontStyleCache[styleString]) {
                return fontStyleCache[styleString];
            }
            var el = document.createElement('div');
            var style = el.style;
            var fontFamily;
            try {
                style.font = styleString;
                fontFamily = style.fontFamily.split(',')[0];
            } catch (ex) {
            }
            return fontStyleCache[styleString] = {
                style: style.fontStyle || DEFAULT_STYLE.style,
                variant: style.fontVariant || DEFAULT_STYLE.variant,
                weight: style.fontWeight || DEFAULT_STYLE.weight,
                size: style.fontSize || DEFAULT_STYLE.size,
                family: fontFamily || DEFAULT_STYLE.family
            };
        }
        function getComputedStyle(style, element) {
            var computedStyle = {};
            for (var p in style) {
                computedStyle[p] = style[p];
            }
            // Compute the size
            var canvasFontSize = parseFloat(element.currentStyle.fontSize), fontSize = parseFloat(style.size);
            if (typeof style.size == 'number') {
                computedStyle.size = style.size;
            } else if (style.size.indexOf('px') != -1) {
                computedStyle.size = fontSize;
            } else if (style.size.indexOf('em') != -1) {
                computedStyle.size = canvasFontSize * fontSize;
            } else if (style.size.indexOf('%') != -1) {
                computedStyle.size = canvasFontSize / 100 * fontSize;
            } else if (style.size.indexOf('pt') != -1) {
                computedStyle.size = fontSize / 0.75;
            } else {
                computedStyle.size = canvasFontSize;
            }
            // Different scaling between normal text and VML text. This was found using
            // trial and error to get the same size as non VML text.
            //computedStyle.size *= 0.981;
            return computedStyle;
        }
        function buildStyle(style) {
            return style.style + ' ' + style.variant + ' ' + style.weight + ' ' + style.size + 'px \'' + style.family + '\'';
        }
        var lineCapMap = {
            'butt': 'flat',
            'round': 'round'
        };
        function processLineCap(lineCap) {
            return lineCapMap[lineCap] || 'square';
        }
        function createShapeAttr() {
            return {
                filled: false,
                stroked: false,
                path: '',
                fillStyle: null,
                strokeStyle: null,
                globalAlpha: 1,
                lineCap: 'butt',
                lineJoin: 'miter',
                lineWidth: 1,
                miterlimit: Z * 1,
                x: 0,
                y: 0
            };
        }
        function copyShapeAttr(o1, o2) {
            o1.path = o2.path;
            o1.fillStyle = o2.fillStyle;
            o1.globalAlpha = o2.globalAlpha;
            // PENDING When shape changed from not stroked to stroked
            if (o2.stroked) {
                o1.strokeStyle = o2.strokeStyle;
                o1.lineCap = o2.lineCap;
                o1.lineJoin = o2.lineJoin;
                o1.lineWidth = o2.lineWidth;
                o1.miterlimit = o2.miterlimit;
            }
            o1.x = o2.x;
            o1.y = o2.y;
            o1.filled = o2.filled;
            o1.stroked = o2.stroked;
        }
        function createTextAttr() {
            var attr = createShapeAttr();
            attr.text = '';
            attr.font = '12px 微软雅黑';
            attr.textAlign = 'left';
            attr.textBaseline = 'alphabetic';
            attr.offX = 0;
            attr.offY = 0;
            attr.maxWidth = 0;
            return attr;
        }
        function copyTextAttr(o1, o2) {
            copyShapeAttr(o1, o2);
            o1.text = o2.text;
            o1.font = o2.font;
            o1.textAlign = o2.textAlign;
            o1.textBaseline = o2.textBaseline;
            o1.offX = o2.offX;
            o1.offY = o2.offY;
            o1.maxWidth = o2.maxWidth;
        }
        function createImageAttr() {
            return {
                image: '',
                // position after tranformed
                x: 0,
                y: 0,
                padding: '',
                skewM: '',
                cropped: false,
                width: 0,
                height: 0,
                globalAlpha: 1
            };
        }
        function copyImageAttr(o1, o2) {
            o1.image = o2.image;
            o1.x = o2.x;
            o1.y = o2.y;
            o1.width = o2.width;
            o1.height = o2.height;
            o1.globalAlpha = o2.globalAlpha;
            if (o2.skewed) {
                o1.skewM = o2.skewM;
                o1.padding = o2.padding;
            }
            if (o2.cropped) {
                o1.cropWidth = o2.cropWidth;
                o1.cropHeight = o2.cropHeight;
                o1.cropFilter = o2.cropFilter;
            }
            o1.cropped = o2.cropped;
            o1.skewed = o2.skewed;
        }
        /**
   * Virtual shape dom is created by stroke and fill operation.
   * It will be cached in Context2D object. And created only if needed when redrawing
   * @author https://github.com/pissang/
   */
        function ShapeVirtualDom_() {
            // this.rootEl_ = null;
            // this.strokeEl_ = null;
            // this.fillEl_ = null;
            this.attr_ = createShapeAttr();
            this.attrPrev_ = {};
        }
        ShapeVirtualDom_.prototype.attachTo = function (el) {
            if (!this.attached_) {
                var p = this.rootEl_.parentNode;
                if (p !== el) {
                    el.appendChild(this.rootEl_);
                }
            }
            this.attached_ = true;
        };
        ShapeVirtualDom_.prototype.detach = function () {
            if (this.attached_) {
                var p = this.rootEl_.parentNode;
                if (p) {
                    p.removeChild(this.rootEl_);
                }
            }
            this.attached_ = false;
        };
        ShapeVirtualDom_.prototype.getElement = function (path) {
            if (!this.rootEl_) {
                this.createShapeEl_(path);
            }
            var attr_ = this.attr_;
            attr_.path = path;
            attr_.filled = false;
            attr_.stroked = false;
            return this.rootEl_;
        };
        ShapeVirtualDom_.prototype.createShapeEl_ = function (path) {
            var W = 10;
            var H = 10;
            var rootEl_ = createVMLElement('shape');
            rootEl_.style.cssText = [
                'position:absolute;width:',
                W,
                'px;height:',
                H,
                'px'
            ].join('');
            rootEl_.coordorigin = '0 0';
            rootEl_.coordsize = Z * W + ' ' + Z * H;
            rootEl_.filled = 'false';
            rootEl_.stroked = 'false';
            this.rootEl_ = rootEl_;
        };
        ShapeVirtualDom_.prototype.isFilled = function () {
            return this.attr_.filled;
        };
        ShapeVirtualDom_.prototype.isStroked = function () {
            return this.attr_.stroked;
        };
        ShapeVirtualDom_.prototype.fill = function (ctx, min, max) {
            var attr_ = this.attr_;
            attr_.filled = true;
            attr_.fillStyle = ctx.fillStyle;
            attr_.globalAlpha = ctx.globalAlpha;
            attr_.x = ctx.x_;
            attr_.y = ctx.y_;
            if (ctx.fillStyle instanceof CanvasGradient_) {
                attr_.m_ = ctx.m_;
                attr_.scaleX = ctx.scaleX_;
                attr_.scaleY = ctx.scaleY_;
                attr_.min = min;
                attr_.max = max;
            } else if (ctx.fillStyle instanceof CanvasPattern_) {
                attr_.scaleX = ctx.scaleX_;
                attr_.scaleY = ctx.scaleY_;
                attr_.min = min;
                attr_.max = max;
            }
        };
        ShapeVirtualDom_.prototype.stroke = function (ctx) {
            var attr_ = this.attr_;
            attr_.stroked = true;
            attr_.globalAlpha = ctx.globalAlpha;
            attr_.lineCap = ctx.lineCap;
            attr_.lineJoin = ctx.lineJoin;
            attr_.lineWidth = ctx.lineWidth * ctx.lineScale_;
            attr_.miterlimit = ctx.miterlimit;
            attr_.strokeStyle = ctx.strokeStyle;
            attr_.x = ctx.x_;
            attr_.y = ctx.y_;
        };
        ShapeVirtualDom_.prototype.doFill_ = function () {
            var attr_ = this.attr_;
            var attrPrev_ = this.attrPrev_;
            if (attr_.filled !== attrPrev_.filled) {
                var rootEl_ = this.rootEl_;
                if (attr_.filled) {
                    rootEl_.filled = 'true';
                    if (!this.fillEl_) {
                        this.fillEl_ = createVMLElement('fill');    // PENDING 
                                                                    // Set default attribute ?
                    }
                    rootEl_.appendChild(this.fillEl_);
                } else {
                    rootEl_.filled = 'false';
                    if (this.fillEl_) {
                        rootEl_.removeChild(this.fillEl_);
                    }
                }
            }
            if (!attr_.filled) {
                return;
            }
            var fillEl_ = this.fillEl_;
            var fillStyle = attr_.fillStyle;
            if (fillStyle !== attrPrev_.fillStyle || attr_.globalAlpha !== attrPrev_.globalAlpha) {
                // TODO Canvas gradient and pattern still not be optimized
                // There problem when canvas gradient add color stop dynamically
                // 
                // Text fill doesn't support Gradient or Pattern
                if (fillStyle instanceof CanvasGradient_ && attr_.min) {
                    // TODO: Gradients transformed with the transformation matrix.
                    var angle = 0;
                    var focus = {
                        x: 0,
                        y: 0
                    };
                    // additional offset
                    var shift = 0;
                    // scale factor for offset
                    var expansion = 1;
                    var scaleX = attr_.scaleX_;
                    var scaleY = attr_.scaleY_;
                    var min = attr_.min;
                    var max = attr_.max;
                    var width = max.x - min.x;
                    var height = max.y - min.y;
                    if (fillStyle.type_ == 'gradient') {
                        var x0 = fillStyle.x0_ / scaleX;
                        var y0 = fillStyle.y0_ / scaleY;
                        var x1 = fillStyle.x1_ / scaleX;
                        var y1 = fillStyle.y1_ / scaleY;
                        var p0 = getCoords(ctx, x0, y0);
                        var p1 = getCoords(ctx, x1, y1);
                        var dx = p1.x - p0.x;
                        var dy = p1.y - p0.y;
                        angle = Math.atan2(dx, dy) * 180 / Math.PI;
                        // The angle should be a non-negative number.
                        if (angle < 0) {
                            angle += 360;
                        }
                        // Very small angles produce an unexpected result because they are
                        // converted to a scientific notation string.
                        if (angle < 0.000001) {
                            angle = 0;
                        }
                    } else {
                        var p0 = getCoords(ctx, fillStyle.x0_, fillStyle.y0_);
                        focus = {
                            x: (p0.x - min.x) / width,
                            y: (p0.y - min.y) / height
                        };
                        width /= scaleX * Z;
                        height /= scaleY * Z;
                        var dimension = m.max(width, height);
                        shift = 2 * fillStyle.r0_ / dimension;
                        expansion = 2 * fillStyle.r1_ / dimension - shift;
                    }
                    // We need to sort the color stops in ascending order by offset,
                    // otherwise IE won't interpret it correctly.
                    var stops = fillStyle.colors_;
                    stops.sort(function (cs1, cs2) {
                        return cs1.offset - cs2.offset;
                    });
                    var length = stops.length;
                    var color1 = stops[0].color;
                    var color2 = stops[length - 1].color;
                    var opacity1 = stops[0].alpha * attr_.globalAlpha;
                    var opacity2 = stops[length - 1].alpha * attr_.globalAlpha;
                    var colors = [];
                    for (var i = 0; i < length; i++) {
                        var stop = stops[i];
                        colors.push(stop.offset * expansion + shift + ' ' + stop.color);
                    }
                    fillEl_.type = fillStyle.type_;
                    fillEl_.method = 'none';
                    fillEl_.focus = '100%';
                    fillEl_.color = color1;
                    fillEl_.color2 = color2;
                    fillEl_.colors = colors.join(',');
                    fillEl_.opacity = opacity2;
                    fillEl_.setAttribute('g_o_:opacity2', opacity1);
                    fillEl_.angle = angle;
                    fillEl_.focusposition = focus.x + ',' + focus.y;
                } else if (fillStyle instanceof CanvasPattern_ && attr_.min) {
                    if (width && height) {
                        var deltaLeft = -attr_.min.x;
                        var deltaTop = -attr_.min.y;
                        fillEl_.position = deltaLeft / width * scaleX * scaleX + ',' + deltaTop / height * scaleY * scaleY;
                        fillEl_.type = 'tile';
                        fillEl_.src = fillStyle.src_;
                    }
                } else {
                    var a = processStyle(fillStyle);
                    var color = a.color;
                    var opacity = a.alpha * attr_.globalAlpha;
                    fillEl_.color = color;
                    if (opacity < 1) {
                        fillEl_.opacity = opacity;
                    }
                }
            }
        };
        ShapeVirtualDom_.prototype.doStroke_ = function () {
            var attr_ = this.attr_;
            var attrPrev_ = this.attrPrev_;
            if (attr_.stroked !== attrPrev_.stroked) {
                var rootEl_ = this.rootEl_;
                if (attr_.stroked) {
                    if (!this.strokeEl_) {
                        this.strokeEl_ = createVMLElement('stroke');    // PENDING 
                                                                        // Set default attribute ?
                    }
                    rootEl_.stroked = 'true';
                    rootEl_.appendChild(this.strokeEl_);
                } else {
                    rootEl_.stroked = 'false';
                    if (this.strokeEl_) {
                        rootEl_.removeChild(this.strokeEl_);
                    }
                }
            }
            if (!attr_.stroked) {
                return;
            }
            if (attr_.strokeStyle !== attrPrev_.strokeStyle || attr_.globalAlpha !== attrPrev_.globalAlpha || attr_.lineWidth !== attrPrev_.lineWidth) {
                var a = processStyle(attr_.strokeStyle);
                var opacity = a.alpha * attr_.globalAlpha;
                var lineWidth = attr_.lineWidth;
                // VML cannot correctly render a line if the width is less than 1px.
                // In that case, we dilute the color to make the line look thinner.
                if (lineWidth < 1) {
                    opacity *= lineWidth;
                }
                if (opacity < 1) {
                    this.strokeEl_.opacity = opacity;
                }
                this.strokeEl_.color = a.color;
            }
            if (attr_.lineJoin !== attrPrev_.lineJoin) {
                this.strokeEl_.joinstyle = attr_.lineJoin;
            }
            if (attr_.miterLimit !== attrPrev_.miterLimit) {
                this.strokeEl_.miterlimit = attr_.miterLimit;
            }
            if (attr_.lineCap !== attrPrev_.lineCap) {
                this.strokeEl_.endcap = processLineCap(attr_.lineCap);
            }
            if (lineWidth !== attrPrev_.lineWidth) {
                this.strokeEl_.weight = lineWidth + 'px';
            }
        };
        ShapeVirtualDom_.prototype.flush = function (ctx) {
            var attr_ = this.attr_;
            var attrPrev_ = this.attrPrev_;
            if (attr_.x !== attrPrev_.x) {
                this.rootEl_.style.left = attr_.x + 'px';
            }
            if (attr_.y !== attrPrev_.y) {
                this.rootEl_.style.top = attr_.y + 'px';
            }
            if (attr_.path !== attrPrev_.path) {
                this.rootEl_.path = attr_.path;
            }
            this.doFill_();
            this.doStroke_();
            copyShapeAttr(attrPrev_, attr_);
        };
        /**
   * Virtual text dom is created by fillText and strokeText operation.
   * It will be cached in Context2D object. And created only if needed when redrawing
   * @author https://github.com/pissang/
   */
        function TextVirtualDom_() {
            // this.rootEl_ = null;
            // this.skewEl_ = null;
            // this.textPathEl_ = null;
            // this.simpleRootEl_ = null;
            this.attr_ = createTextAttr();
            this.attrPrev_ = {};
        }
        TextVirtualDom_.prototype.getElement = function (ctx, text, x, y, maxWidth, stroke) {
            if (!this.rootEl_) {
                this.createEl_();
            }
            var m_ = ctx.m_;
            var attr_ = this.attr_;
            attr_.text = text;
            attr_.sx = x;
            attr_.sy = y;
            attr_.maxWidth = maxWidth;
            attr_.textAlign = ctx.textAlign;
            attr_.textBaseline = ctx.textBaseline;
            attr_.stroked = !!stroke;
            attr_.filled = !stroke;
            var fontStyle = getComputedStyle(processFontStyle(ctx.font), ctx.element_);
            var fontStyleString = buildStyle(fontStyle);
            attr_.font = fontStyleString;
            var offset = {
                x: 0,
                y: 0
            };
            // 1.75 is an arbitrary number, as there is no info about the text baseline
            switch (ctx.textBaseline) {
            case 'hanging':
            case 'top':
                offset.y = fontStyle.size / 1.75;
                break;
            case 'middle':
                break;
            default:
            case null:
            case 'alphabetic':
            case 'ideographic':
            case 'bottom':
                offset.y = -fontStyle.size / 2.25;
                break;
            }
            var d = getCoords(ctx, x + offset.x, y + offset.y);
            attr_.offX = d.x;
            attr_.offY = d.y;
            // attr_.skewed = isNotAroundZero(m_[0] - 1) || isNotAroundZero(m_[1]) ||
            // isNotAroundZero(m_[3] - 1) || isNotAroundZero(m_[2])
            attr_.skewM = m_[0][0].toFixed(3) + ',' + m_[1][0].toFixed(3) + ',' + m_[0][1].toFixed(3) + ',' + m_[1][1].toFixed(3);
            if (stroke) {
                attr_.globalAlpha = ctx.globalAlpha;
                attr_.lineCap = ctx.lineCap;
                attr_.lineJoin = ctx.lineJoin;
                attr_.lineWidth = ctx.lineWidth * ctx.lineScale_;
                attr_.miterlimit = ctx.miterlimit;
                attr_.strokeStyle = ctx.strokeStyle;
            } else {
                attr_.fillStyle = ctx.fillStyle;
                attr_.globalAlpha = ctx.globalAlpha;
            }
            // TODO It is strange that flush after the rootEl has been appended to document
            // SkewOffset like '10, 10'(which one item is not zero) will cause the shape disappeared.
            this.flush(ctx);
            return this.rootEl_;
        };
        TextVirtualDom_.prototype.createEl_ = function () {
            var W = 10;
            var H = 10;
            this.rootEl_ = createVMLElement('line');
            var rootEl_ = this.rootEl_;
            rootEl_.coordsize = Z * W + ' ' + Z * H;
            rootEl_.coordorigin = '0 0';
            rootEl_.style.cssText = 'position:absolute;width:1px;height:1px';
            rootEl_.stroked = 'false';
            rootEl_.filled = 'false';
        };
        TextVirtualDom_.prototype.flush = function (ctx) {
            var m_ = ctx.m_;
            var delta = 1000;
            var left = 0;
            var right = delta;
            var attr_ = this.attr_;
            var attrPrev_ = this.attrPrev_;
            var rootEl_ = this.rootEl_;
            if (!this.skewEl_) {
                this.skewEl_ = createVMLElement('skew');
                this.skewEl_.on = 't';
                this.textPathEl_ = createVMLElement('textpath');
                this.pathEl_ = createVMLElement('path');
                this.pathEl_.textpathok = 'true';
                this.textPathEl_.on = 'true';
                rootEl_.appendChild(this.skewEl_);
                rootEl_.appendChild(this.pathEl_);
                rootEl_.appendChild(this.textPathEl_);
            }
            var fontStyle = getComputedStyle(processFontStyle(this.attr_.font), ctx.element_);
            if (attr_.font !== attrPrev_.font || attr_.text !== attrPrev_.text) {
                this.textPathEl_.string = encodeHtmlAttribute(attr_.text);
                this.textPathEl_.style.font = encodeHtmlAttribute(attr_.font);
            }
            if (attr_.textAlign !== attrPrev_.textAlign) {
                var elementStyle = ctx.element_.currentStyle;
                var textAlign = attr_.textAlign.toLowerCase();
                switch (textAlign) {
                case 'left':
                case 'center':
                case 'right':
                    break;
                case 'end':
                    textAlign = elementStyle.direction == 'ltr' ? 'right' : 'left';
                    break;
                case 'start':
                    textAlign = elementStyle.direction == 'rtl' ? 'right' : 'left';
                    break;
                default:
                    textAlign = 'left';
                }
                switch (textAlign) {
                case 'right':
                    left = delta;
                    right = 0.05;
                    break;
                case 'center':
                    left = right = delta / 2;
                    break;
                }
                rootEl_.from = -left + ' 0';
                rootEl_.to = right + ' 0.05';
                this.skewEl_.origin = left + ' 0';
                this.textPathEl_.style['v-text-align'] = textAlign;
            }
            // if (attr_.skewed || stroke) {
            if (attr_.skewM !== attrPrev_.skewM) {
                this.skewEl_.matrix = attr_.skewM + ',0,0';
            }
            if (attr_.offX !== attrPrev_.offX || attr_.offY !== attrPrev_.offY) {
                var skewOffset = mr(attr_.offX / Z) + ',' + mr(attr_.offY / Z);
                this.skewEl_.offset = skewOffset;
            }
            if (attr_.stroked) {
                this.doStroke_();
            } else {
                this.doFill_();
            }
            copyTextAttr(attrPrev_, attr_);    // } else {
                                               //   if (!this.simpleRootEl_) {
                                               //     this.simpleRootEl_ = document.createElement('div');
                                               //     this.simpleRootEl_.style.position = 'absolute';
                                               //   }
                                               //   this.simpleRootEl_.style.font = encodeHtmlAttribute(fontStyleString);
                                               //   var a = processStyle(ctx.fillStyle);
                                               //   var color = a.color;
                                               //   var opacity = a.alpha * ctx.globalAlpha;
                                               //   this.simpleRootEl_.style.color = color;
                                               //   if (opacity < 1) {
                                               //     this.simpleRootEl_.style.filter = 'alpha(opacity=' + mr(opacity * 100) +')';
                                               //   }
                                               //   this.simpleRootEl_.innerHTML = text;
                                               //   switch (ctx.textBaseline) {
                                               //     case 'hanging':
                                               //     case 'top':
                                               //       this.simpleRootEl_.style.top = m_[2][1] + y + 'px';
                                               //       break;
                                               //     case 'middle':
                                               //       // TODO
                                               //       this.simpleRootEl_.style.top = m_[2][1] + y - fontStyle.size / 2.25 + 'px';
                                               //       break;
                                               //     default:
                                               //     case null:
                                               //     case 'alphabetic':
                                               //     case 'ideographic':
                                               //     case 'bottom':
                                               //     //
                                               //       this.simpleRootEl_.style.bottom = ctx.element_.clientHeight - m_[2][1] - y + 'px';
                                               //       break;
                                               //   }
                                               //   switch(textAlign) {
                                               //     case 'right':
                                               //       this.simpleRootEl_.style.right = ctx.element_.clientWidth - m_[2][0] - x + 'px';
                                               //       break;
                                               //     case 'center':
                                               //       // TODO
                                               //       this.simpleRootEl_.style.left = m_[2][0] + x - fontStyle.size / 4.5 * text.length + 'px';
                                               //       break;
                                               //     case 'left':
                                               //       this.simpleRootEl_.style.left = m_[2][0] + x + 'px';
                                               //       break;
                                               //   }
                                               //   return this.simpleRootEl_;
                                               // }
        };
        TextVirtualDom_.prototype.doFill_ = ShapeVirtualDom_.prototype.doFill_;
        TextVirtualDom_.prototype.doStroke_ = ShapeVirtualDom_.prototype.doStroke_;
        TextVirtualDom_.prototype.attachTo = ShapeVirtualDom_.prototype.attachTo;
        TextVirtualDom_.prototype.detach = ShapeVirtualDom_.prototype.detach;
        /**
   * Virtual image dom is created by drawImage operation.
   * It will be cached in Context2D object. And created only if needed when redrawing
   * @author https://github.com/pissang/
   *
   * TODO Image cropping testing
   */
        function ImageVirtualDom_() {
            // this.rootEl_ = null;
            // this.cropEl_ = null;
            // this.imageEl_ = null;
            // this.groupEl_ = null;
            this.attr_ = createImageAttr();
            this.attrPrev_ = {};
        }
        ;
        ImageVirtualDom_.prototype.getElement = function (ctx, image, var_args) {
            var dx, dy, dw, dh, sx, sy, sw, sh;
            // to find the original width we overide the width and height
            var oldRuntimeWidth = image.runtimeStyle.width;
            var oldRuntimeHeight = image.runtimeStyle.height;
            var m_ = ctx.m_;
            image.runtimeStyle.width = 'auto';
            image.runtimeStyle.height = 'auto';
            // get the original size
            var w = image.width;
            var h = image.height;
            // and remove overides
            image.runtimeStyle.width = oldRuntimeWidth;
            image.runtimeStyle.height = oldRuntimeHeight;
            var args = Array.prototype.slice.call(arguments, 1);
            var attr_ = this.attr_;
            attr_.globalAlpha = ctx.globalAlpha;
            var scaleX = ctx.scaleX_;
            var scaleY = ctx.scaleY_;
            if (args.length == 3) {
                dx = args[1];
                dy = args[2];
                sx = sy = 0;
                sw = dw = w;
                sh = dh = h;
            } else if (args.length == 5) {
                dx = args[1];
                dy = args[2];
                dw = args[3];
                dh = args[4];
                sx = sy = 0;
                sw = w;
                sh = h;
            } else if (args.length == 9) {
                sx = args[1];
                sy = args[2];
                sw = args[3];
                sh = args[4];
                dx = args[5];
                dy = args[6];
                dw = args[7];
                dh = args[8];
            } else {
                throw Error('Invalid number of arguments');
            }
            // Have rotation
            attr_.skewed = m_[0][1] || m_[1][0];
            if (attr_.skewed) {
                var d = getCoords(ctx, dx, dy);
                attr_.x = d.x;
                attr_.y = d.y;
                var filter = [];
                filter.push('M11=', m_[0][0] / scaleX, ',', 'M12=', m_[1][0] / scaleY, ',', 'M21=', m_[0][1] / scaleX, ',', 'M22=', m_[1][1] / scaleY, ',', 'Dx=', d.x, ',', 'Dy=', d.y, '');
                attr_.skewM = filter.join('');
                // Bounding box calculation (need to minimize displayed area so that
                // filters don't waste time on unused pixels.
                var max = d;
                var c2 = getCoords(ctx, dx + dw, dy);
                var c3 = getCoords(ctx, dx, dy + dh);
                var c4 = getCoords(ctx, dx + dw, dy + dh);
                max.x = m.max(max.x, c2.x, c3.x, c4.x);
                max.y = m.max(max.y, c2.y, c3.y, c4.y);
                attr_.padding = [
                    0,
                    Math.max(mr(max.x / Z), 0) + 'px',
                    Math.max(mr(max.y / Z), 0) + 'px',
                    0
                ].join(' ');
            } else {
                attr_.x = dx * scaleX + ctx.x_;
                attr_.y = dy * scaleY + ctx.y_;
            }
            attr_.cropped = sx || sy;
            if (attr_.cropped) {
                attr_.cropWidth = Math.ceil((dw + sx * dw / sw) * scaleX);
                attr_.cropHeight = Math.ceil((dh + sy * dh / sh) * scaleY);
                attr_.cropFilter = 'progid:DxImageTransform.Microsoft.Matrix(Dx=' + -dw / sw * scaleX * sx + ',Dy=' + -dh / sh * scaleY * sy + ')';
            }
            attr_.width = scaleX * dw / sw * w;
            attr_.height = scaleY * dh / sh * h;
            attr_.image = image.src;
            if (!this.imageEl_) {
                // NOTES
                // Matrix of rootDom will not work if imageDom.style.position = 'absolute'
                this.imageEl_ = document.createElement('img');
            }
            if (!(attr_.skewed || attr_.cropped)) {
                this.rootEl_ = this.imageEl_;
            } else if (attr_.skewed) {
                if (!this.groupEl_) {
                    this.createGroupEl_();
                }
                this.rootEl_ = this.groupEl_;
            } else {
                if (!this.cropEl_) {
                    this.cropEl_ = document.createElement('div');
                    this.cropEl_.style.cssText = 'position:absolute; overflow:hidden;';
                }
                this.rootEl_ = this.cropEl_;
            }
            this.flush(ctx);
            return this.rootEl_;
        };
        ImageVirtualDom_.prototype.createGroupEl_ = function () {
            var W = 10;
            var H = 10;
            // For some reason that I've now forgotten, using divs didn't work
            this.groupEl_ = createVMLElement('group');
            this.groupEl_.coordsize = Z * W + ' ' + Z * H;
            this.groupEl_.coordorigin = '0 0';
            this.groupEl_.style.cssText = [
                'position:absolute;width:',
                W,
                'px;height:',
                H,
                'px'
            ].join('');
        };
        ImageVirtualDom_.prototype.flush = function (ctx) {
            var attr_ = this.attr_;
            var attrPrev_ = this.attrPrev_;
            var w2 = attr_.sw / 2;
            var h2 = attr_.sh / 2;
            var imageEl_ = this.imageEl_;
            // If filters are necessary (rotation exists), create them
            // filters are bog-slow, so only create them if abbsolutely necessary
            // The following check doesn't account for skews (which don't exist
            // in the canvas spec (yet) anyway.
            if (!attr_.skewed && !attr_.cropped) {
                if (attr_.x !== attrPrev_.x) {
                    imageEl_.style.left = attr_.x + 'px';
                }
                if (attr_.y !== attrPrev_.y) {
                    imageEl_.style.top = attr_.y + 'px';
                }
                if (!attrPrev_.skewed) {
                    imageEl_.style.position = 'absolute';
                } else {
                    imageEl_.style.position = 'static';
                }
            } else if (attr_.skewed) {
                var groupEl_ = this.groupEl_;
                if (attr_.padding !== attrPrev_.padding) {
                    groupEl_.style.padding = attr_.padding;
                }
                if (attr_.skewM !== attrPrev_.skewM) {
                    groupEl_.style.filter = 'progid:DXImageTransform.Microsoft.Matrix(' + attr_.skewM + ', SizingMethod=\'clip\')';
                }
                if (attr_.cropped) {
                    if (!attrPrev_.cropped) {
                        groupEl_.appendChild(this.cropEl_);
                        this.cropEl_.appendChild(imageEl_);
                    }
                } else {
                    if (!attrPrev_.skewed) {
                        groupEl_.appendChild(imageEl_);
                    }
                }
            } else if (attr_.cropped) {
                if (!attrPrev_.cropped) {
                    this.cropEl_.appendChild(imageEl_);
                }
            }
            // Draw a special cropping div if needed
            if (attr_.cropped) {
                var groupEl_ = this.groupEl_;
                if (attr_.cropWidth !== attrPrev_.cropWidth) {
                    this.cropEl_.style.width = attr_.cropWidth + 'px';
                }
                if (attr_.cropHeight !== attrPrev_.cropHeight) {
                    this.cropEl_.style.height = attr_.cropHeight + 'px';
                }
                if (attr_.filter !== attrPrev_.filter) {
                    this.cropEl_.style.filter = attr_.filter;
                }
            }
            if (attr_.width !== attrPrev_.width) {
                imageEl_.style.width = attr_.width + 'px';
            }
            if (attr_.height !== attrPrev_.height) {
                imageEl_.style.height = attr_.height + 'px';
            }
            if (attr_.image !== attrPrev_.image) {
                imageEl_.src = attr_.image;
            }
            if (attr_.globalAlpha !== attrPrev_.globalAlpha) {
                if (imageEl_.style.globalAlpha < 1) {
                    imageEl_.style.filter = 'alpha(opacity=' + mr(attr_.globalAlpha * 100) + ')';
                } else {
                    imageEl_.style.filter = '';
                }
            }
            copyImageAttr(this.attrPrev_, this.attr_);
        };
        ImageVirtualDom_.prototype.attachTo = ShapeVirtualDom_.prototype.attachTo;
        ImageVirtualDom_.prototype.detach = ShapeVirtualDom_.prototype.detach;
        /**
   * This class implements CanvasRenderingContext2D interface as described by
   * the WHATWG.
   * @param {HTMLElement} canvasElement The element that the 2D context should
   * be associated with
   */
        function CanvasRenderingContext2D_(canvasElement) {
            this.m_ = createMatrixIdentity();
            this.mStack_ = [];
            this.aStack_ = [];
            this.currentPath_ = [];
            // NOTES
            // http://louisremi.com/2009/03/30/changes-in-vml-for-ie8-or-what-feature-can-the-ie-dev-team-break-for-you-today/
            // It is no longer possible to create a VML element outside of the DOM
            // this.fragment_ = document.createDocumentFragment();
            // Keep current drawed dom. So we can merge fill and stroke in one shape dom
            this.currentVirtualDom_ = null;
            // Cache the created dom
            this.shapeVDomList_ = [];
            this.textVDomList_ = [];
            this.imageVDomList_ = [];
            this.nShapeVEl_ = 0;
            this.nTextVEl_ = 0;
            this.nImageVEl_ = 0;
            // Canvas context properties
            this.strokeStyle = '#000';
            this.fillStyle = '#000';
            this.lineWidth = 1;
            this.lineJoin = 'miter';
            this.lineCap = 'butt';
            this.miterLimit = Z * 1;
            this.globalAlpha = 1;
            // this.font = '10px sans-serif';
            this.font = '12px 微软雅黑';
            // 决定还是改这吧，影响代价最小
            this.textAlign = 'left';
            this.textBaseline = 'alphabetic';
            this.canvas = canvasElement;
            var cssText = 'width:' + canvasElement.clientWidth + 'px;height:' + canvasElement.clientHeight + 'px;overflow:hidden;position:absolute';
            var el = canvasElement.ownerDocument.createElement('div');
            el.style.cssText = cssText;
            canvasElement.appendChild(el);
            var overlayEl = el.cloneNode(false);
            // Use a non transparent background.
            overlayEl.style.backgroundColor = '#fff';
            //red, I don't know why, it work! 
            overlayEl.style.filter = 'alpha(opacity=0)';
            canvasElement.appendChild(overlayEl);
            this.element_ = el;
            this.scaleX_ = 1;
            this.scaleY_ = 1;
            this.lineScale_ = 1;
            this.ghost_ = document.createElement('div');
            var cssText = 'position:absolute; left:0px; right: 0px; top: 0px; bottom: 0px;';
            this.ghost_.style.cssText = cssText;
            this.element_.appendChild(this.ghost_);
            this.x_ = 0;
            this.y_ = 0;
        }
        var contextPrototype = CanvasRenderingContext2D_.prototype;
        contextPrototype.clearRect = function () {
            if (this.textMeasureEl_) {
                this.textMeasureEl_.removeNode(true);
                this.textMeasureEl_ = null;
            }
            // var ghost_ = this.ghost_;
            // Hide everything
            this.ghost_.style.display = 'none';
            // NOTES: Using innerHTML = '' will cause all descendant elements detached
            // while (ghost_.firstChild) {
            //   ghost_.removeChild(ghost_.firstChild);
            // }
            // NOTES: removeChild in IE8 will not set the parentNode to null
            // 
            // TODO Remove ghost element before change the attributes of children each frame is even more slow
            // if (ghost_.parentNode === this.element_) {
            //   this.element_.removeChild(ghost_);
            // }
            this.currentVirtualDom_ = null;
            this.nShapeVEl_ = 0;
            this.nTextVEl_ = 0;
            this.nImageVEl_ = 0;
        };
        contextPrototype.flush = function () {
            for (var i = 0; i < this.nShapeVEl_; i++) {
                this.shapeVDomList_[i].flush(this);
            }
            // Show everything
            this.ghost_.style.display = 'block';
            for (var i = this.nShapeVEl_, len = this.shapeVDomList_.length; i < len; i++) {
                this.shapeVDomList_[i].detach();
            }
            for (var i = this.nImageVEl_, len = this.imageVDomList_.length; i < len; i++) {
                this.imageVDomList_[i].detach();
            }
            for (var i = this.nTextVEl_, len = this.textVDomList_.length; i < len; i++) {
                this.textVDomList_[i].detach();
            }
            this.shapeVDomList_.length = this.nShapeVEl_;
            this.imageVDomList_.length = this.nImageVEl_;
            this.textVDomList_.length = this.nTextVEl_;    // this.element_.appendChild(this.ghost_);
        };
        contextPrototype.beginPath = function () {
            // TODO: Branch current matrix so that save/restore has no effect
            //       as per safari docs.
            this.currentPath_ = [];
            this.currentVirtualDom_ = null;
        };
        contextPrototype.moveTo = function (aX, aY) {
            var p = getSkewedCoords(this, aX, aY);
            p.type = 'moveTo';
            this.currentPath_.push(p);
            this.currentX_ = p.x;
            this.currentY_ = p.y;
        };
        contextPrototype.lineTo = function (aX, aY) {
            var p = getSkewedCoords(this, aX, aY);
            p.type = 'lineTo';
            this.currentPath_.push(p);
            this.currentX_ = p.x;
            this.currentY_ = p.y;
            this.currentVirtualDom_ = null;
        };
        contextPrototype.bezierCurveTo = function (aCP1x, aCP1y, aCP2x, aCP2y, aX, aY) {
            var p = getSkewedCoords(this, aX, aY);
            var cp1 = getSkewedCoords(this, aCP1x, aCP1y);
            var cp2 = getSkewedCoords(this, aCP2x, aCP2y);
            bezierCurveTo(this, cp1, cp2, p);
            this.currentVirtualDom_ = null;
        };
        // Helper function that takes the already fixed cordinates.
        function bezierCurveTo(self, cp1, cp2, p) {
            self.currentPath_.push({
                type: 'bezierCurveTo',
                cp1x: cp1.x,
                cp1y: cp1.y,
                cp2x: cp2.x,
                cp2y: cp2.y,
                x: p.x,
                y: p.y
            });
            self.currentX_ = p.x;
            self.currentY_ = p.y;
            this.currentVirtualDom_ = null;
        }
        contextPrototype.quadraticCurveTo = function (aCPx, aCPy, aX, aY) {
            // the following is lifted almost directly from
            // http://developer.mozilla.org/en/docs/Canvas_tutorial:Drawing_shapes
            var cp = getSkewedCoords(this, aCPx, aCPy);
            var p = getSkewedCoords(this, aX, aY);
            var cp1 = {
                x: this.currentX_ + 2 / 3 * (cp.x - this.currentX_),
                y: this.currentY_ + 2 / 3 * (cp.y - this.currentY_)
            };
            var cp2 = {
                x: cp1.x + (p.x - this.currentX_) / 3,
                y: cp1.y + (p.y - this.currentY_) / 3
            };
            bezierCurveTo(this, cp1, cp2, p);
            this.currentVirtualDom_ = null;
        };
        contextPrototype.arc = function (aX, aY, aRadius, aStartAngle, aEndAngle, aClockwise) {
            aRadius *= Z;
            var arcType = aClockwise ? 'at' : 'wa';
            var xStart = aX + mc(aStartAngle) * aRadius - Z2;
            var yStart = aY + ms(aStartAngle) * aRadius - Z2;
            var xEnd = aX + mc(aEndAngle) * aRadius - Z2;
            var yEnd = aY + ms(aEndAngle) * aRadius - Z2;
            // IE won't render arches drawn counter clockwise if xStart == xEnd.
            if (xStart == xEnd && !aClockwise) {
                xStart += 0.125;    // Offset xStart by 1/80 of a pixel. Use something
                                    // that can be represented in binary
            }
            var p = getSkewedCoords(this, aX, aY);
            var pStart = getSkewedCoords(this, xStart, yStart);
            var pEnd = getSkewedCoords(this, xEnd, yEnd);
            this.currentPath_.push({
                type: arcType,
                x: p.x,
                y: p.y,
                radius: aRadius,
                xStart: pStart.x,
                yStart: pStart.y,
                xEnd: pEnd.x,
                yEnd: pEnd.y
            });
            this.currentVirtualDom_ = null;
        };
        contextPrototype.rect = function (aX, aY, aWidth, aHeight) {
            this.moveTo(aX, aY);
            this.lineTo(aX + aWidth, aY);
            this.lineTo(aX + aWidth, aY + aHeight);
            this.lineTo(aX, aY + aHeight);
            this.closePath();
            this.currentVirtualDom_ = null;
        };
        contextPrototype.strokeRect = function (aX, aY, aWidth, aHeight) {
            var oldPath = this.currentPath_;
            this.beginPath();
            this.moveTo(aX, aY);
            this.lineTo(aX + aWidth, aY);
            this.lineTo(aX + aWidth, aY + aHeight);
            this.lineTo(aX, aY + aHeight);
            this.closePath();
            this.stroke();
            this.currentPath_ = oldPath;
        };
        contextPrototype.fillRect = function (aX, aY, aWidth, aHeight) {
            var oldPath = this.currentPath_;
            this.beginPath();
            this.moveTo(aX, aY);
            this.lineTo(aX + aWidth, aY);
            this.lineTo(aX + aWidth, aY + aHeight);
            this.lineTo(aX, aY + aHeight);
            this.closePath();
            this.fill();
            this.currentPath_ = oldPath;
        };
        contextPrototype.createLinearGradient = function (aX0, aY0, aX1, aY1) {
            var gradient = new CanvasGradient_('gradient');
            gradient.x0_ = aX0;
            gradient.y0_ = aY0;
            gradient.x1_ = aX1;
            gradient.y1_ = aY1;
            return gradient;
        };
        contextPrototype.createRadialGradient = function (aX0, aY0, aR0, aX1, aY1, aR1) {
            var gradient = new CanvasGradient_('gradientradial');
            gradient.x0_ = aX0;
            gradient.y0_ = aY0;
            gradient.r0_ = aR0;
            gradient.x1_ = aX1;
            gradient.y1_ = aY1;
            gradient.r1_ = aR1;
            return gradient;
        };
        contextPrototype.drawImage = function (image, var_args) {
            var vDom = this.imageVDomList_[this.nImageVEl_];
            if (!vDom) {
                vDom = new ImageVirtualDom_();
                this.imageVDomList_[this.nImageVEl_] = vDom;
            }
            this.nImageVEl_++;
            var args = Array.prototype.slice.call(arguments);
            args.unshift(this);
            var el = vDom.getElement.apply(vDom, args);
            vDom.attachTo(this.ghost_);
            this.currentVirtualDom_ = null;
        };
        contextPrototype.stroke = function (aFill) {
            if (this.currentVirtualDom_) {
                // Simply append fill or stroke dom
                if (aFill && !this.currentVirtualDom_.isFilled()) {
                    this.currentVirtualDom_.fill(this);
                } else if (!aFill && !this.currentVirtualDom_.isStroked()) {
                    this.currentVirtualDom_.stroke(this);
                }
                return;
            }
            var pathStr = [];
            var min = {
                x: null,
                y: null
            };
            var max = {
                x: null,
                y: null
            };
            for (var i = 0; i < this.currentPath_.length; i++) {
                var p = this.currentPath_[i];
                var c;
                switch (p.type) {
                case 'moveTo':
                    c = p;
                    pathStr.push(' m ', mr(p.x), ',', mr(p.y));
                    break;
                case 'lineTo':
                    pathStr.push(' l ', mr(p.x), ',', mr(p.y));
                    break;
                case 'close':
                    pathStr.push(' x ');
                    p = null;
                    break;
                case 'bezierCurveTo':
                    pathStr.push(' c ', mr(p.cp1x), ',', mr(p.cp1y), ',', mr(p.cp2x), ',', mr(p.cp2y), ',', mr(p.x), ',', mr(p.y));
                    break;
                case 'at':
                case 'wa':
                    pathStr.push(' ', p.type, ' ', mr(p.x - this.scaleX_ * p.radius), ',', mr(p.y - this.scaleY_ * p.radius), ' ', mr(p.x + this.scaleX_ * p.radius), ',', mr(p.y + this.scaleY_ * p.radius), ' ', mr(p.xStart), ',', mr(p.yStart), ' ', mr(p.xEnd), ',', mr(p.yEnd));
                    break;
                }
                // TODO: Following is broken for curves due to
                //       move to proper paths.
                // Figure out dimensions so we can do gradient fills
                // properly
                if (p) {
                    if (min.x == null || p.x < min.x) {
                        min.x = p.x;
                    }
                    if (max.x == null || p.x > max.x) {
                        max.x = p.x;
                    }
                    if (min.y == null || p.y < min.y) {
                        min.y = p.y;
                    }
                    if (max.y == null || p.y > max.y) {
                        max.y = p.y;
                    }
                }
            }
            pathStr = pathStr.join('');
            var vDom = this.shapeVDomList_[this.nShapeVEl_];
            if (!vDom) {
                vDom = new ShapeVirtualDom_();
                this.shapeVDomList_[this.nShapeVEl_] = vDom;
            }
            this.nShapeVEl_++;
            var shapeEl = vDom.getElement(pathStr, this.x_, this.y_);
            aFill ? vDom.fill(this, min, max) : vDom.stroke(this);
            vDom.attachTo(this.ghost_);
            this.currentVirtualDom_ = vDom;
            return shapeEl;
        };
        contextPrototype.fill = function () {
            return this.stroke(true);
        };
        contextPrototype.closePath = function () {
            this.currentPath_.push({ type: 'close' });
        };
        function getCoords(ctx, aX, aY) {
            var m = ctx.m_;
            return {
                x: Z * (aX * m[0][0] + aY * m[1][0] + m[2][0]) - Z2,
                y: Z * (aX * m[0][1] + aY * m[1][1] + m[2][1]) - Z2
            };
        }
        ;
        function getSkewedCoords(ctx, aX, aY) {
            var m = ctx.m_;
            return {
                x: Z * (aX * m[0][0] + aY * m[1][0]) - Z2,
                y: Z * (aX * m[0][1] + aY * m[1][1]) - Z2
            };
        }
        contextPrototype.save = function () {
            var o = {};
            copyState(this, o);
            this.aStack_.push(o);
            this.mStack_.push(this.m_);
            this.m_ = matrixMultiply(createMatrixIdentity(), this.m_);
        };
        contextPrototype.restore = function () {
            if (this.aStack_.length) {
                copyState(this.aStack_.pop(), this);
                this.m_ = this.mStack_.pop();
            }
        };
        function matrixIsFinite(m) {
            return isFinite(m[0][0]) && isFinite(m[0][1]) && isFinite(m[1][0]) && isFinite(m[1][1]) && isFinite(m[2][0]) && isFinite(m[2][1]);
        }
        function setM(ctx, m, updateLineScale) {
            if (!matrixIsFinite(m)) {
                return;
            }
            ctx.m_ = m;
            ctx.scaleX_ = Math.sqrt(m[0][0] * m[0][0] + m[0][1] * m[0][1]);
            ctx.scaleY_ = Math.sqrt(m[1][0] * m[1][0] + m[1][1] * m[1][1]);
            ctx.x_ = m[2][0];
            ctx.y_ = m[2][1];
            if (updateLineScale) {
                // Get the line scale.
                // Determinant of this.m_ means how much the area is enlarged by the
                // transformation. So its square root can be used as a scale factor
                // for width.
                var det = m[0][0] * m[1][1] - m[0][1] * m[1][0];
                ctx.lineScale_ = sqrt(abs(det));
            }
        }
        contextPrototype.translate = function (aX, aY) {
            var m1 = [
                [
                    1,
                    0,
                    0
                ],
                [
                    0,
                    1,
                    0
                ],
                [
                    aX,
                    aY,
                    1
                ]
            ];
            setM(this, matrixMultiply(m1, this.m_), false);
        };
        contextPrototype.rotate = function (aRot) {
            var c = mc(aRot);
            var s = ms(aRot);
            var m1 = [
                [
                    c,
                    s,
                    0
                ],
                [
                    -s,
                    c,
                    0
                ],
                [
                    0,
                    0,
                    1
                ]
            ];
            setM(this, matrixMultiply(m1, this.m_), false);
        };
        contextPrototype.scale = function (aX, aY) {
            var m1 = [
                [
                    aX,
                    0,
                    0
                ],
                [
                    0,
                    aY,
                    0
                ],
                [
                    0,
                    0,
                    1
                ]
            ];
            setM(this, matrixMultiply(m1, this.m_), true);
        };
        contextPrototype.transform = function (m11, m12, m21, m22, dx, dy) {
            var m1 = [
                [
                    m11,
                    m12,
                    0
                ],
                [
                    m21,
                    m22,
                    0
                ],
                [
                    dx,
                    dy,
                    1
                ]
            ];
            setM(this, matrixMultiply(m1, this.m_), true);
        };
        contextPrototype.setTransform = function (m11, m12, m21, m22, dx, dy) {
            var m = [
                [
                    m11,
                    m12,
                    0
                ],
                [
                    m21,
                    m22,
                    0
                ],
                [
                    dx,
                    dy,
                    1
                ]
            ];
            setM(this, m, true);
        };
        /**
   * The text drawing function.
   * The maxWidth argument isn't taken in account, since no browser supports
   * it yet.
   */
        contextPrototype.drawText_ = function (text, x, y, maxWidth, stroke) {
            var vDom = this.textVDomList_[this.nTextVEl_];
            if (!vDom) {
                vDom = new TextVirtualDom_();
                this.textVDomList_[this.nTextVEl_] = vDom;
            }
            this.nTextVEl_++;
            var el = vDom.getElement(this, text, x, y, maxWidth, stroke);
            vDom.attachTo(this.ghost_);
            this.currentVirtualDom_ = null;
        };
        contextPrototype.fillText = function (text, x, y, maxWidth) {
            this.drawText_(text, x, y, maxWidth, false);
        };
        contextPrototype.strokeText = function (text, x, y, maxWidth) {
            this.drawText_(text, x, y, maxWidth, true);
        };
        contextPrototype.measureText = function (text) {
            if (!this.textMeasureEl_) {
                var s = '<span style="position:absolute;' + 'top:-20000px;left:0;padding:0;margin:0;border:none;' + 'white-space:pre;"></span>';
                this.element_.insertAdjacentHTML('beforeEnd', s);
                this.textMeasureEl_ = this.element_.lastChild;
            }
            var doc = this.element_.ownerDocument;
            this.textMeasureEl_.innerHTML = '';
            this.textMeasureEl_.style.font = this.font;
            // Don't use innerHTML or innerText because they allow markup/whitespace.
            this.textMeasureEl_.appendChild(doc.createTextNode(text));
            return { width: this.textMeasureEl_.offsetWidth };
        };
        /******** STUBS ********/
        contextPrototype.clip = function () {
        };
        contextPrototype.arcTo = function () {
        };
        contextPrototype.createPattern = function (image, repetition) {
            return new CanvasPattern_(image, repetition);
        };
        // Gradient / Pattern Stubs
        function CanvasGradient_(aType) {
            this.type_ = aType;
            this.x0_ = 0;
            this.y0_ = 0;
            this.r0_ = 0;
            this.x1_ = 0;
            this.y1_ = 0;
            this.r1_ = 0;
            this.colors_ = [];
        }
        CanvasGradient_.prototype.addColorStop = function (aOffset, aColor) {
            aColor = processStyle(aColor);
            this.colors_.push({
                offset: aOffset,
                color: aColor.color,
                alpha: aColor.alpha
            });
        };
        function CanvasPattern_(image, repetition) {
            assertImageIsValid(image);
            switch (repetition) {
            case 'repeat':
            case null:
            case '':
                this.repetition_ = 'repeat';
                break;
            case 'repeat-x':
            case 'repeat-y':
            case 'no-repeat':
                this.repetition_ = repetition;
                break;
            default:
                throwException('SYNTAX_ERR');
            }
            this.src_ = image.src;
            this.width_ = image.width;
            this.height_ = image.height;
        }
        function throwException(s) {
            throw new DOMException_(s);
        }
        function assertImageIsValid(img) {
            if (!img || img.nodeType != 1 || img.tagName != 'IMG') {
                throwException('TYPE_MISMATCH_ERR');
            }
            if (img.readyState != 'complete') {
                throwException('INVALID_STATE_ERR');
            }
        }
        function DOMException_(s) {
            this.code = this[s];
            this.message = s + ': DOM Exception ' + this.code;
        }
        var p = DOMException_.prototype = new Error();
        p.INDEX_SIZE_ERR = 1;
        p.DOMSTRING_SIZE_ERR = 2;
        p.HIERARCHY_REQUEST_ERR = 3;
        p.WRONG_DOCUMENT_ERR = 4;
        p.INVALID_CHARACTER_ERR = 5;
        p.NO_DATA_ALLOWED_ERR = 6;
        p.NO_MODIFICATION_ALLOWED_ERR = 7;
        p.NOT_FOUND_ERR = 8;
        p.NOT_SUPPORTED_ERR = 9;
        p.INUSE_ATTRIBUTE_ERR = 10;
        p.INVALID_STATE_ERR = 11;
        p.SYNTAX_ERR = 12;
        p.INVALID_MODIFICATION_ERR = 13;
        p.NAMESPACE_ERR = 14;
        p.INVALID_ACCESS_ERR = 15;
        p.VALIDATION_ERR = 16;
        p.TYPE_MISMATCH_ERR = 17;
        // set up externs
        G_vmlCanvasManager = G_vmlCanvasManager_;
        CanvasRenderingContext2D = CanvasRenderingContext2D_;
        CanvasGradient = CanvasGradient_;
        CanvasPattern = CanvasPattern_;
        DOMException = DOMException_;
    }());
}    // if
else {
    // make the canvas test simple by kener.linfeng@gmail.com
    G_vmlCanvasManager = false;
}
module.exports = G_vmlCanvasManager || module.exports;;    // define
